Deprecate QGuiApplication::paletteChanged() signal

Rather than have a paletteChanged() signal which can be connected to for
tracking when the application palette has changed, then it is better to
use the event that is sent to all windows and the application itself.
That way it is easy for a window/widget or item that cares about the
change to the application font to catch it in the event() function.

[ChangeLog][QtGui][QGuiApplication] Deprecated paletteChanged() signal
in favor of QEvent::ApplicationPaletteChanged.

Change-Id: I95da211e30590e357007cc14d8ee266baceba7b3
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 35 insertions, 0 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 54ca37e638..991211062f 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -418,6 +418,7 @@ private slots:
     void winIdAfterClose();
     void receivesLanguageChangeEvent();
     void receivesApplicationFontChangeEvent();
+    void receivesApplicationPaletteChangeEvent();
 
 private:
     bool ensureScreenSize(int width, int height);
@@ -4988,6 +4989,7 @@ void tst_QWidget::isOpaque()
         QVERIFY(!::isOpaque(&widget));
 
         QApplication::setPalette(old);
+        QApplication::sendPostedEvents(&widget, QEvent::ApplicationPaletteChange);
         QCOMPARE(::isOpaque(&widget), old.color(QPalette::Window).alpha() == 255);
     }
 #endif
@@ -11662,6 +11664,7 @@ public:
     ChangeEventWidget(QWidget *parent = nullptr) : QWidget(parent) {}
     int languageChangeCount = 0;
     int applicationFontChangeCount = 0;
+    int applicationPaletteChangeCount = 0;
 protected:
     bool event(QEvent *e) override
     {
@@ -11669,6 +11672,8 @@ protected:
             languageChangeCount++;
         else if (e->type() == QEvent::ApplicationFontChange)
             applicationFontChangeCount++;
+        else if (e->type() == QEvent::ApplicationPaletteChange)
+            applicationPaletteChangeCount++;
         return QWidget::event(e);
     }
 };
@@ -11679,6 +11684,7 @@ public:
     ChangeEventWindow(QWindow *parent = nullptr) : QWindow(parent) {}
     int languageChangeCount = 0;
     int applicationFontChangeCount = 0;
+    int applicationPaletteChangeCount = 0;
 protected:
     bool event(QEvent *e) override
     {
@@ -11686,6 +11692,8 @@ protected:
             languageChangeCount++;
         else if (e->type() == QEvent::ApplicationFontChange)
             applicationFontChangeCount++;
+        else if (e->type() == QEvent::ApplicationPaletteChange)
+            applicationPaletteChangeCount++;
         return QWindow::event(e);
     }
 };
@@ -11739,5 +11747,32 @@ void tst_QWidget::receivesApplicationFontChangeEvent()
     QApplication::setFont(origFont);
 }
 
+void tst_QWidget::receivesApplicationPaletteChangeEvent()
+{
+    // Confirm that any QWindow or top level QWidget only gets a single
+    // ApplicationPaletteChange event when the font is changed
+    const QPalette origPalette = QApplication::palette();
+
+    ChangeEventWidget topLevel;
+    auto childWidget = new ChangeEventWidget(&topLevel);
+    topLevel.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&topLevel));
+    ChangeEventWindow ww;
+    ww.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&ww));
+    ChangeEventWidget topLevelNotShown;
+    QPalette changedPalette = origPalette;
+    changedPalette.setColor(QPalette::Base, Qt::red);
+    QApplication::setPalette(changedPalette);
+    QCoreApplication::sendPostedEvents(0, QEvent::ApplicationPaletteChange);
+    QCOMPARE(topLevel.applicationPaletteChangeCount, 1);
+    QCOMPARE(topLevelNotShown.applicationPaletteChangeCount, 1);
+    // QWidget should not be passing the event on automatically
+    QCOMPARE(childWidget->applicationPaletteChangeCount, 0);
+    QCOMPARE(ww.applicationPaletteChangeCount, 1);
+
+    QApplication::setPalette(origPalette);
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"